Every 40 seconds, one person in the U.S. has a stroke. Stroke is the fourth leading cause of death overall (third leading among women), it accounts for one of every 18 deaths in the U.S., and it is the third leading cause of death in China. Data from the Sino-MONICA-Beijing Project indicate that the incidence of ischemic stroke in 25-74 year old individuals has doubled between 1984 and 2004, from 100.5 to 213.2 per 100,000. Stroke is also the leading cause of serious, long-term disability. Amongst ischemic stroke survivors 65 years of age and older, 50% have some hemiparesis, 30% are unable to walk without assistance, 19% have aphasia, and 26% are institutionalized in a nursing home six months following their ischemic event. In 2008, the direct and indirect cost of stroke in the U.S. was $34.3 billion2 and projected costs in 2050 exceed $2.2 trillion, leading to calls for greater focus on secondary stroke prevention in the U.S. and in China. The goal of this research is to provide imaging techniques that will help clinicians select the most appropriate treatment strategy for the individual patient. We aim to accomplish this goal through development of improved methods for the detection and localization of the atherosclerotic lesion responsible for stroke, referred to as the culprit plaque. Furthermore, we seek to provide insight into novel markers and risk factors for development of the high-risk plaque. Findings from this study will lay the foundation for prospective studies that will assess whether presence of an MRI-detected culprit plaque poses a higher risk for recurrent stroke, and whether specific circulating markers predict progression to a high-risk plaque.